Table 1.
Baseline clinicopathological characteristics
| Pure ductal BC n (%) n = 3969 |
Pure lobular BC n (%) n = 135 |
P value | |
|---|---|---|---|
| Region | 0.002 | ||
| North America | 319 (8.0) | 11 (8.1) | |
| South-Center America | 130 (3.3) | 5 (3.7) | |
| Asia + Israel | 727 (18.3) | 7 (5.2) | |
| Oceania | 140 (3.5) | 4 (3.0) | |
| North Europe | 620 (15.6) | 28 (20.7) | |
| South Europe | 1793 (45.2) | 65 (48.1) | |
| East Europe | 240 (6.0) | 15 (11.1) | |
| Year of diagnosis | 0.053 | ||
| 2000-2004 | 498 (12.5) | 25 (18.5) | |
| 2005-2008 | 636 (16.0) | 28 (20.7) | |
| 2009-2012 | 867 (21.8) | 19 (14.1) | |
| 2013-2016 | 966 (24.3) | 31 (23.0) | |
| 2017-2020 | 1002 (25.2) | 32 (23.7) | |
| Age at diagnosis, median (IQR) years | 35 (31 to 37) | 36 (33 to 39) | 0.018 |
| Menopausal status at diagnosis | 0.068 | ||
| Premenopausal | 3774 (95.1) | 124 (91.8) | |
| Peri-menopausal | 13 (0.3) | 1 (0.7) | |
| Post-menopausal | 91 (2.3) | 7 (5.2) | |
| Missing | 91 (2.3) | 3 (2.2) | |
| BRCA status | <0.001 | ||
| BRCA1 | 2606 (65.7) | 38 (28.1) | |
| BRCA2 | 1335 (33.6) | 96 (71.1) | |
| BRCA1 and BRCA2 | 23 (0.6) | 1 (0.7) | |
| BRCA pathogenic variant (unknown if 1 or 2) | 5 (0.1) | 0 (0.0) | |
| Time from diagnosis to BRCA testing, median (IQR) months | 5.3 (0.9-25.3) | 8.1 (1.5-44.6) | 0.081 |
| Missing date of BRCA testing | 500 | 13 | |
| Body mass index | 0.741 | ||
| <18.5 | 207 (5.2) | 9 (6.7) | |
| 18.5-24.9 | 2132 (53.7) | 72 (53.3) | |
| 25.0-29.9 | 660 (16.6) | 26 (19.3) | |
| ≥30 | 350 (8.8) | 10 (7.4) | |
| Missing | 620 (15.6) | 18 (13.3) | |
| Stage at breast cancer diagnosis | 0.002 | ||
| I | 1053 (26.5) | 25 (18.5) | |
| II | 2092 (52.7) | 67 (49.6) | |
| III | 734 (18.5) | 40 (29.6) | |
| Missing | 90 (2.3) | 3 (2.2) | |
| Tumor grade | <0.001 | ||
| G1 | 53 (1.3) | 11 (8.1) | |
| G2 | 826 (20.8) | 67 (49.6) | |
| G3 | 2774 (69.9) | 40 (29.6) | |
| Missing | 316 (8.0) | 17 (12.6) | |
| Tumor size | 0.001 | ||
| T1 | 1545 (38.9) | 42 (31.1) | |
| T2 | 1764 (44.4) | 53 (39.3) | |
| T3-T4 | 532 (13.4) | 33 (24.4) | |
| Missing | 128 (3.2) | 7 (5.2) | |
| Nodal status | <0.001 | ||
| N0 | 2063 (52.0) | 48 (35.6) | |
| N1 | 1321 (33.3) | 59 (43.7) | |
| N2-N3 | 474 (11.9) | 25 (18.5) | |
| Missing | 111 (2.8) | 3 (2.2) | |
| Laterality | 0.104 | ||
| Left | 1905 (48.0) | 73 (54.1) | |
| Right | 1900 (47.9) | 61 (45.2) | |
| Bilateral | 152 (3.8) | 1 (0.7) | |
| Missing | 12 (0.3) | 0 (0.0) | |
| Breast surgery | 0.011 | ||
| Not done | 11 (0.3) | 1 (0.7) | |
| Breast conserving surgery | 1603 (40.4) | 37 (27.4) | |
| Mastectomy | 2314 (58.3) | 93 (68.9) | |
| Missing | 41 (1.0) | 4 (3.0) | |
| Tumor subtype | <0.001 | ||
| Luminal A | 484 (12.2) | 57 (42.2) | |
| Luminal B | 865 (21.8) | 33 (24.4) | |
| TNBC | 2049 (51.6) | 19 (14.1) | |
| HER2-positive | 282 (7.1) | 8 (5.9) | |
| Missing | 289 (7.3) | 18 (13.3) | |
| Use of radiotherapy | 0.576 | ||
| No | 1301 (32.8) | 42 (31.1) | |
| Yes | 2592 (65.3) | 93 (68.9) | |
| Missing | 76 (1.9) | 0 (0.0) | |
| Type of systemic treatment | 0.471 | ||
| Not done | 47 (1.2) | 1 (0.7) | |
| Neoadjuvant | 1713 (43.2) | 52 (38.5) | |
| Adjuvant | 2176 (54.8) | 81 (60.0) | |
| Missing | 33 (0.8) | 1 (0.7) | |
| Use of chemotherapy | <0.001 | ||
| No | 258 (6.5) | 21 (15.6) | |
| Yes | 3689 (92.9) | 113 (83.7) | |
| Missing | 22 (0.5) | 1 (0.7) | |
| Type of chemotherapy (for CT = yes) | 0.780 | ||
| Anthracycline- and taxane-based | 2607 (70.7) | 82 (72.6) | |
| Anthracycline-based | 697 (18.9) | 17 (15.0) | |
| Taxane-based | 155 (4.2) | 4 (3.5) | |
| Others | 113 (3.1) | 4 (3.5) | |
| Missing | 117 (3.2) | 6 (5.3) | |
| Use of endocrine therapy (for HR+) | 0.277 | ||
| No | 83 (4.8) | 3 (2.6) | |
| Yes | 1624 (93.9) | 111 (97.4) | |
| Missing | 23 (1.3) | 0 (0.0) | |
| Type of endocrine therapy (for HR+ and ET = yes) | 0.896 | ||
| Tamoxifen alone | 566 (34.8) | 37 (33.3) | |
| Tamoxifen + LHRHa | 465 (28.6) | 32 (28.8) | |
| LHRHa alone | 28 (1.7) | 1 (0.9) | |
| AI ± LHRHa | 277 (17.1) | 23 (20.7) | |
| Tamoxifen and AI (± LHRHa) | 250 (15.4) | 15 (13.5) | |
| Others | 23 (1.4) | 2 (1.8) | |
| Missing | 15 (0.9) | 1 (0.9) | |
| Use of anti-HER2 therapy (for HER2+) | 0.843 | ||
| No | 28 (9.9) | 1 (12.5) | |
| Yes | 243 (86.2) | 7 (87.5) | |
| Missing | 11 (3.9) | 0 (0.0) | |
| Bilateral risk-reducing mastectomy | 0.422 | ||
| No | 1651 (41.6) | 51 (37.8) | |
| Yes | 2257 (56.9) | 81 (60.0) | |
| Missing | 61 (1.5) | 3 (2.2) | |
| Bilateral risk-reducing salpingo-oophorectomy | 0.598 | ||
| No | 1849 (46.6) | 60 (44.4) | |
| Yes | 2045 (51.5) | 74 (54.8) | |
| Missing | 75 (1.9) | 1 (0.7) |
AI, aromatase inhibitor; BC, breast cancer; CT, chemotherapy; ET, endocrine therapy; HER2, human epidermal growth factor receptor 2; HR, hormone receptor; IQR, interquartile range; LHRHa, luteinizing hormone-releasing hormone analog; TNBC, triple-negative breast cancer.